One of the big selling points for Pokémon X and Ywas the introduction of Mega Evolutions. Sun and Moon sees the return of this feature, as well as the introduction of another crystal-based mechanic that, while not as cool as Mega Evolutions, tweaks gameplay in an important way. Players are given a device called a Z-Ring that allows them to hold Z-Crystals, which can be found hidden throughout the Alola region. These crystals can be used in battle to unleash a devestating super move, but only if the Pokémon being used has a move that corresponds to the crystal type.
A Z-Move can only be used once per battle and players can hold up to six crystals at a time. Nintendo is pushing Z-Moves to such a degree that they’re actually selling a peripheral that you can wear on your wrist while you play the game. The device is pretty silly and unnecessary, but it will at least make battles more lively affairs thanks to its light-up abilities and sound effects.